Page:Popular Science Monthly Volume 34.djvu/233

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knowledge let us put ourselves in his place, and then we may comprehend the exultation with which he announces the identity of radiant heat and common air, for he feels that he is beginning a daring revolt against the orthodox doctrine of caloric, and so he is.

[To be continued.]

By J. M. FRENCH, M. D.

IT is a startling fact, which meets the student of vital statistics at the outset of his investigations, that from one third to one half of all persons born into the world die before reaching the age of five years. Or, to face the terrible reality from another point of view, so great are the dangers of infancy, that a child which has completed its fifth year actually has an expectation of life more than twelve years greater than it had at birth.

The exact proportion of deaths varies greatly in different countries and localities, at different times and under different circumstances. Statistics are of value only in showing average results. In Norway, for example, the proportion dying under five is stated by Dr. Farr to be 204·5 per 1,000 born; while in England it is 338 per 1,000, and in Italy 567 per 1,000. In fifty-one so-called "healthy districts" of England and Wales, according to the same authority, the mortality under five is 175 per 1,000 born, while in the Liverpool district, representing the most unfavorable sanitary conditions, it is 460 per 1,000.

In the different parts of our own country, we find nearly as great a variety as on the continent of Europe. Even in the same latitude, the proportion varies greatly, according as city or country districts are considered. In the State of Vermont, which contains no large cities, and represents essentially a rural population, the number of deaths under five, for the year 1883, was 23·8 per cent of the whole number of deaths; in the State of Massachusetts, which embraces several large cities within its limits, for the twelve years ending in 1884, it was 34·74 per cent; and in the city of New York alone, for the seven years ending in 1873, it was exactly 50 per cent of the entire mortality.

The younger the child, the larger is the death-rate. According to Dr. Jacobi, more than half of those who die under five years of age die in the first year. Dr. Curtiss states that, in all the great cities of North America, out of every one hundred live-born children, about twenty-five die before the end of the first year, and from forty to fifty before the close of the fifth year.

Death-rates like these—and the figures might be multiplied